The invention is directed to polyacrylate esters with long-chain alkoxylated hydrocarbonoxy groups and their use as emulsifiers, solubilizers and thickeners for aqueous, anionic surfactant-containing solutions, particularly in cosmetics and personal grooming. More particularly, the invention relates to polyacrylate esters with a reduced content of low molecular weight or oligomeric compounds, as well as with a distribution of polymers which approximates a Poisson distribution, and particularly to those polyacrylate esters, which have improved physiological properties.
Copolymers of polyoxyalkylene (meth)acrylate esters and alkyl (meth)acrylate esters are known from the art.
For example, in Japanese Published Patent Application 61/145254, organic and inorganic pigments are described, the surfaces of which are treated with a copolymer which consists of 1 to 99% by weight of polyoxyalkylene (meth)acrylate and 1 to 99% by weight of alkyl (meth)acrylate and the alkyl group of the alkyl methacrylate has 6 to 22 carbon atoms. These copolymers increase the dispersibility of pigments which have been treated with them.
From German Offenlegungsschrift 36 36 429, polymeric surfactants are known which are based on copolymers of hydrophobic and hydrophilic monomers and which contain in copolymerized form (a) as hydrophobic monomers, compounds of formula ##STR1## in which R=H or CH.sub.3
X=C.sub.4 to C.sub.20 alkyl or ##STR2## R.sup.1 =H, C.sub.1 to C.sub.20 alkyl or halogen ##STR3## n=1 to 4 R.sup.2, R.sup.3 =H, C.sub.1 to C.sub.20 alkyl, F, Cl, Br, and PA1 Y= ##STR5## R.sup.4 =H, CH.sub.3 or C.sub.2 H.sub.5 R.sup.5 =H, Cl to C.sub.4 alkyl and PA1 m=2 to 50. PA1 R is either a hydrogen group and R' is a hydrogen group or an alkyl group with 1 to 4 carbon atoms, or PA1 R is a --COOX group and R' is a hydrogen group or the --CH.sub.2 COOX group, or PA1 R is a methyl group and R' is a hydrogen group, and PA1 X is a hydrogen group or an alkyl group with 1 to 4 carbon atoms PA1 Y is a hydrogen group and Z is a --COOR, --C.sub.6 H.sub.4 R'--, --CN--, Cl--, --OOCR''-- or --CH.dbd.CH.sub.2 group or PA1 Y is a methyl group and Z a --COOR--, --C.sub.6 H.sub.4 R'--, --CN-- or --CH=CH.sub.2 group or PA1 Y and Z are chloro groups and PA1 R is an alkyl group with 1 to 8 carbon atoms or a hydroxyalkyl group with 2 to 8 carbon atoms, PA1 R' is a hydrogen, chloro, bromo or alkyl group with 1 to 4 carbon atoms and PA1 R'' is an alkyl group with 1 to 8 carbon atoms, and PA1 R'' is an alkyl group with 8 to 20 carbon atoms or an alkylphenyl group with 8 to 16 carbon atoms, PA1 n on the average is a number from 6 to 100 and PA1 m on the average is a number from 0 to 50, with the proviso that n.gtoreq.m and (n+m) is equal to 6 to 100. PA1 R.sup.1 is an alkyl group with 8 to 30 carbon atoms, an alkenyl group with 8 to 22 carbon atoms or a monoalkyl- or dialkylphenyl group with 6 to 16 carbon atoms per alkyl group, wherein up to 40% of the Ri groups may be replaced by alkyl groups with 1 to 4 carbon atoms, PA1 n has a value of 2, 3 or 4 and an average value of 2.0 to 2.5 in the average molecule and PA1 x has a value of 10 to 200,
(b) as hydrophilic monomers, compounds of the formula ##STR4## in which R=H or CH.sub.3,
In aqueous systems above the critical micelle concentrations, these polymeric surfactants form micellar structures, which, in the case of suitable formations and in particular concentration ranges, are present as liquid crystalline phases (mesophases). The copolymers described in the German Offenlegungsschrift 36 36 429 are intended to make possible a wide variation of mesophasic structures and stability parameters. These copolymers have surfactant properties and the water-soluble compounds can be used in detergent formulations to enhance laundering power. The copolymers furthermore can be used to increase the viscosity of aqueous phases, the viscosity-increasing effect being largely independent of the pH.
European published patent application 0 011 806 relates to a liquid emulsion polymer which has a ph-dependent thickening effect on aqueous preparations and contains
a) 15-60% by weight of an .alpha.,.beta.-ethylenically unsaturated monomeric carboxylic acid of the formula EQU RCH.dbd.C(R')--COOH
wherein
b) 15-80% by weight of at least one nonionic, copolymerizable .alpha.,.beta.-ethylenically unsaturated monomer of the formula EQU CH.sub.2 .dbd.CYZ
wherein
c) 1-30% by weight of a nonionic surface active vinyl ester of the formula ##STR6## wherein R is a hydrogen or methyl group and each R' group is an alkyl group with 1 or 2 carbon
At a pH of less than about 5.0, the polymer is stable in the form of an aqueous colloidal dispersion. However, when the pH is adjusted to a value of 5.5 to 10.5 and higher, it becomes an effective thickener for aqueous systems.
Copolymers of a similar composition are described in U.S. Pat. Nos. 4,469,611 and 4,552,685. Gel chromatographic analysis of these copolymers of the state of the art shows a relatively broad molecular weight distribution, which can be responsible for a decreased surfactant activity. As can furthermore be demonstrated by NMR spectroscopic analysis and gel chromatographic analysis, the copolymers contain appreciable portions of low molecular weight compounds. These low molecular weight portions consist of appreciable amounts of residual monomers as well as of low molecular weight compounds. It is assumed that the cause for this may be found in the polymerization parameters of the different monomers, which differ greatly from one another.
These low molecular weight portions are, however, undesirable in various ways. They adversely affect and diminish the surface active properties of the known copolymers, since they themselves contribute nothing or only very little to these properties. The low molecular weight portions are, however, also undesirable for physiological reasons, since they lead to impairment of health, such as skin irritations, sensitizations, etc.
It is not possible to separate these interfering portions from the copolymers of the state of the art in an economic manner.